John Oates reveals why he shaved his giant mustache in his upcoming memoir “Change of Seasons.”

John Oates, half of the very successful musical duo Hall & Oates, says that in 1987 he received a call from an accountant at their management office.

Oates, now 70, went for a meeting and was bluntly told that he was broke — even after selling 80 million records and touring the world for two decades.

He says that although he owned two New York City apartments, a beautiful house in Connecticut, a condo in Aspen, a plane and a fleet of antique cars, all he could claim title to was the $50 in his wallet.

In his upcoming memoir “Change of Seasons,” the once-mustachioed musician blames ex-manager Tommy Mottola and lawyer Allen Grubman. He’s not accusing the music industry honcho of cheating him; he just wishes that Mottola had told them that the increasingly lavish gifts and huge checks would come at a steep price.

Daryl Hall and John Oates perform during the 2014 Rock and Roll Hall of fame induction ceremony at the Barclays Center.

Oates says he had a sudden epiphany to make a personal change to help usher in a new stage of his life. “No one will ever understand how much that mustache affected my life,” he writes. “It was so much a part of who I had become.”

After living for many years in the Village, Oates says his first marriage to a Ford model failed due to his roving eye.

“I should never have been married in the ’80s,” he writes. “She was a successful model and I was running around the world like I was single.”

He eventually moved to Aspen where he became friendly with legendary journalist Hunter S. Thompson. Oates says he was shocked but not surprised when the “Fear and Loathing in Las Vegas” author committed suicide in 2005.